When an endoscope is being inserted into a body cavity, organ pressure and the like produces a force tending to close the body cavity, which may make it difficult to insert the endoscope without aid. In such cases, a so-called endoscopic overtube (hereinafter referred to as an “overtube” where appropriate) is used widely. When inserted into the body cavity, for example, together with an endoscope, the overtube has the advantage of providing an insertion path into the body cavity for the endoscope, making it easy to insert and withdraw the endoscope subsequently.
In relation to endoscope systems made up of such an overtube and endoscope, there have been proposed various techniques for improving insertability of the endoscope into the deeper digestive tract such as the small and large intestines.
For example, Japanese Patent Laid-Open No. 2002-369791 describes a technique for providing a flexibility adjusting mechanism to an overtube to adjust hardness of the overtube, changing the hardness of the overtube according to hardness of the organs into which the overtube is inserted, and thereby improving insertability.
However, when inserting the endoscope into the deeper digestive tract using the overtube which is subject to hardness adjustment, since the endoscope is inserted along the intestines, an insertion section needs to be as long as the intestines. This means that when the endoscope is inserted into the large intestine, the insertion section needs to be approximately 2 m and that when the endoscope is inserted into the small intestine, the insertion section needs to be 5 m or longer. The long insertion section makes it troublesome to handle and difficult to operate the insertion section.
Japanese Patent Laid-Open No. 11-290263 describes an endoscope system made up of a combination of an endoscope and an overtube (sliding tube), in which a balloon is provided in a distal end portion of each of the endoscope and the overtube, and the endoscope is inserted through repeated inflation/deflation of each balloon and repeated insertion/withdrawal of the endoscope and overtube.
The technique described in Japanese Patent Laid-Open No. 11-290263 has the advantage of reducing the length of an insertion section compared to the length of the intestine because the technique shortens that part of the intestine which is lying on the hand side of the balloons by pulling the endoscope and overtube with the distal end portions of the endoscope and overtube fixed by the inflated balloons. However, since the technique inserts the endoscope and overtube into the deeper digestive tract using flexibility of the insertion section, both endoscope and overtube need to be flexible, and when pushing and inserting the endoscope or overtube, the endoscope and overtube can get bent, making it difficult to insert them.
The present invention has been made in view of the above circumstances and has an object to provide an endoscope system which is easy to insert, being equipped with a relatively short insertion section, as well as to provide an endoscope system control program and endoscope system control method for controlling the endoscope system.